A conventional switch device, especially for those switches using bimetallic plate to prevent from being burn when an overload is happened, generally includes a bimetallic plate which is deformed when overload so as to separate the two contact points respectively located on the bimetallic plate and one of the two terminals. Some inherent shortcomings for these conventional safety switch devices are found. There are too many parts involved in the safety switch device and a longer period of time is required when assembling the switch device, this increases the cost of the products. The parts might be arranged inaccurately and affects the deformation of the bimetallic plate. Once the bimetallic plate is deformed to cut off the circuit, because of the improper arrangement of the parts as mentioned above, the bimetallic plate could deform to re-connect the two contact points to connect the circuit again. Because the inaccuracy of the deformation of the bimetallic plate, the switch member does not set the “OFF” position after the bimetallic plate is deformed to cut off the circuit.
Therefore, it is desired to have a safety device that allows the bimetallic plate to deform toward a desired direction and there is enough space to prevent the bimetallic plate from bouncing back to connect the circuit again.